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Hurricanes & Tropical Storms

Satellite view of a hurricane covering the entire Gulf of Mexico
Satellite image of Hurricane Ike in 2008, as the eye of the storm neared the Flower Garden Banks. Credit: NOAA

Hurricanes are tropical storms that can severely impact reef habitats. Their strong winds create powerful wave action capable of tearing a reef apart and the run-off created by massive quantities of rainwater dumped on land carries sediments and debris out to sea. The potential for destruction underwater is as real as that on land.

So, how do the reefs of Flower Garden Banks National Marine Sanctuary stand up to the onslaught? We've had a few opportunities to find out.

Since 1851, a total of 91 storms have come within 70 miles of East Flower Garden, West Flower Garden, and Stetson Banks. While we haven't been around to witness all of these, we are able to see historical hurricane tracks and learn more about individual storms using an online tool created by NOAA's Office for Coastal Management.

Colored lines criss-cross the Gulf of Mexico showing where different hurricanes have passed.
Historical hurricane tracks near East Flower Garden, West Flower Garden, and Stetson Banks since 1851. Credit: NOAA

Hannah, Laura, Beta, Delta (2020)

The 2020 hurricane season was the most active storm season in the history of the Flower Garden Banks. Three hurricanes and one tropical storm (Beta) crisscrossed the area around the original three sanctuary banks (East, West, Stetson).

As a result, we lost ten mooring buoys, an Ocean Acidification science buoy, and the HI-A-389-A platform marker buoy.

Harvey (2017)

In late August 2017, Hurricane Harvey dumped an unprecedented amount of rain on the Houston/Galveston area of Texas, prompting concerns about excessive freshwater influence on the sanctuary. A Rapid Response team of scientists visited the sanctuary in September 2017 under a National Science Foundation grant to see if they could identify any such impacts, but found that the massive amount of freshwater deposited by Hurricane Harvey never quite reached the sanctuary.

The only visible evidence of Harvey's passing was large ripples in the sand patches. All of the water turnover during Harvey also brought temperatures down to 81F, greatly reducing the threat of bleaching that year.

Large ripples in the sand of an open area between sections of coral reef.
Heavy wave action caused rippling in the sand near East Flower Garden Bank Buoy #5. Credit: Emma Hickerson/FGBNMS

Ike (2008)

In September 2008, the eye of Hurricane Ike passed directly over East Flower Garden Bank. Although it was rated a Category 2 storm, according to wind speed, its enormous size caused it to move water like a Category 4 storm.

In October 2008, sanctuary staff were finally able visit the sanctuary for a quick look at the condition of the reefs. What they saw was reminiscent of the aftermath of Hurricane Rita in 2005.

A diver swims past a large, overturned coral on the reef
Some boulders of coral up to 4 meters across were torn loose from the reef and tossed as much as 25 feet away. Credit: Emma Hickerson/FGBNMS
A diver using an underwater scooter hovers over a large boulder of brain coral lying upside down in the sand.
Other boulders of coral were broken off and toppled alongside their original locations. Credit: Emma Hickerson/FGBNMS
A reddish-colored, multi-lobed sponge on the reef with white sections where it is damaged.
Many of the giant barrel sponges (Xestospongia muta) were sheared off, either completely or partially. Only a few escaped injury. Credit: Emma Hickerson/FGBNMS
A reddish-colored, multi-lobed sponge on the reef with white sections where it is damaged.
Fields of yellow pencil coral (Madracis mirabilis) on the eastern flank of East Flower Garden Bank experienced significant breakage as a result of the downward forces produced by the storm. This area was in similar condition after Hurricane Rita in 2005, but had recovered substantially prior to Hurricane Ike. Credit: Emma Hickerson/FGBNMS

Katrina and Rita (2005)

In August 2005, Hurricane Katrina came roaring into the Gulf and passed well to the east of Flower Garden Banks National Marine Sanctuary. It is believed to have had minimal impact on the reef.

Unfortunately, we were unable to check on the sanctuary before Rita came howling through a few weeks later. The eye of Rita passed 35 miles to the east of East Flower Garden Bank as a Category 3 storm, leaving the entire west side of the storm directly over the sanctuary.

Satellite photos in the weeks after Rita showed a huge swath of brown water reaching from the coast all the way out to the sanctuary, 115 miles offshore. Water quality sensors on site confirmed that this was indeed freshwater, but what nutrients or chemicals it contained we may never know. Needless to say, even coral reefs far from shore may be impacted by storm runoff.

A satellite image of the Gulf of Mexico showing a large patch of brown water coming from the coast and reaching out to the sanctuary
A plume of muddy water flowed over 100 miles offshore and into the sanctuary following Hurricane Rita in 2005. Credit: NASA

In November 2008, we were finally able to check on the reefs. Some of Rita's physical impacts at the sanctuary were significant, affecting items as deep as 72 meters.

Bare coral rock is exposed at the base of a coral outcrop where sand has been pushed away.
As much as 3 feet of sand was scoured from around the bases of some coral outcroppings, leaving old coral rock exposed. Credit: Joyce and Frank Burek
Scientific instruments partially buried in sand near the reef.
Sand scoured away from some sections, was piled up in other areas, sometimes impacting scientific instruments on the sea floor. Credit: Joyce and Frank Burek
Corals showing exposed skeleton in areas where large pieces were broken off.
Some corals at the Flower Garden Banks were broken and their pieces scattered, exposing sections of reef that were previously hidden. Credit: Joyce and Frank Burek
Bare rock showing its natural striations.
At Stetson Bank, wave action scoured sections of siltstone, leaving bare rock where sponges and algae once grew. Credit: Joyce and Frank Burek

But, there was a positive aspect to this storm, too. Hurricane Rita left cooler water in her wake, which benefited corals experiencing one of the worst bleaching episodes ever seen in the sanctuary.